#include <bits/stdc++.h>
using namespace std;
#define all(v) (v).begin(), (v).end()
using ll = long long;
using ld = long double;
using pint = pair<int, int>;
using pll = pair<ll, ll>;

int main() {
    int H, W, N; cin >> H >> W >> N;
    vector<int> a(N), b(N), c(N), d(N);
    for (int i = 0; i < N; i++) {
        cin >> a[i] >> b[i] >> c[i] >> d[i];
    }
    int ans = 2e9+7;
    vector<int> usd(N, 0), md(N, 2e9);
    function<void(int, int, int)> dfs = [&](int y, int x, int dist) {
        ans = min(dist + (H - y) + (W - x), ans);
        for (int i = 0; i < N; i++) {
            if (usd[i]) continue;
            usd[i] = 1;
            int ndist = dist + abs(a[i] - y) + abs(b[i] - x) + 1;
            if (ndist >= md[i]) continue;
            md[i] = ndist;
            dfs(c[i], d[i], ndist);
            usd[i] = 0;
        }
    };
    dfs(1, 1, 0);
    cout << ans << endl;
}